(μmol/s)/(PPFD) with respect to Hang height

Hey guys, I'm looking for fixture PAR maps and the μmol/s output for the PAR measurements taken. Doesn't matter if it's lensed or not. If you've a saved PAR map on your phone or computer, post it up, thanks!

1. Total μmol/s:
2. PAR map(s)

Trying to asses real world correlation between PPFD, μmol/s, hang height, and fixture design.

UVB is EMR just like visible light, so if we can get an idea of how many visible photons are emitted (μmol/J) vs how many are hitting canopy (PPFD), we should be able calculate UV needs.

Inverse square law is great, but it's modeled after a point source emitting in all directions. An LED emits in one direction and is reflected in the fixture, as well as the chip housing. Lenses will throw the basic understanding of this principle off as well. I'm trying to determine what the real world correlation is between PPFD & μmol/s with respect to hang height and certain fixture designs.

EDIT:
If the light shines like a cone, I think you can use the ratio of the big circle vs the small circle and calculate theoretical ppfd for big circle (pretty accurately) if total μmol/s and beam angle are known for the little circle, or the chip?

Here ya go Chief.....

And there's more.....

Lol

Haha you da man! Thanks! That's quite the haul! Thread closed! Lol

ya i think that was a mic drop moment for moflow lol

Finished my Arse.....

I think I can calculate mean PPFD vs height and group similar reflector types and fixtures together to get an idea of intensity per height. Not sure how useful it will be though

That's what I'm talking bout @Moflow haha

Thanks for all the charts, awesome info all in one space.

HOnestly, I don't know why some people try to say that the inverse square law doesn't apply to LED(each LED is an individual light source). Most of these par charts show the ISL in full effect.

Obviously adding more LEDs in a balanced pattern like the fluence spyder does, helps to mask the loss by utilizing the overlap from the surrounding LEDs to provide a balanced intensity. This definitely helps coverage and intensity but doesn't actually change the physics of what is happening with the light. Every 6" the lights are moved the ppfd drops very predictably. Because of the overlap it blurs the line on the exact percentage of drop per diode, but its the same principle.

Anyway, I'm not talking trash, just something that has surprised me. I love how even a canopy intensity can be achieved with LEDs!

Hehe....

Thundercat said:

Thanks for all the charts, awesome info all in one space.

HOnestly, I don't know why some people try to say that the inverse square law doesn't apply to LED(each LED is an individual light source). Most of these par charts show the ISL in full effect.

Obviously adding more LEDs in a balanced pattern like the fluence spyder does, helps to mask the loss by utilizing the overlap from the surrounding LEDs to provide a balanced intensity. This definitely helps coverage and intensity but doesn't actually change the physics of what is happening with the light. Every 6" the lights are moved the ppfd drops very predictably. Because of the overlap it blurs the line on the exact percentage of drop per diode, but its the same principle.

Anyway, I'm not talking trash, just something that has surprised me. I love how even a canopy intensity can be achieved with LEDs!

Click to expand...

Its not that the ISL isn't observed, it's just that it's mis-interpreted. Same in the case of a laser. The ISL still holds true but the multiplying coefficient is different. Ill have to go back and review but the reason I'm saying that LED doesn't follow the most commonly modeled ISL is due to it being based on a spherical point source emmision with intensity diminishing on the surface of the sphere at a rate in relation to the inverse square of its radius length, whereas an LED emits in a cone shape and diminishes intensity at the surface of the cone at a different rate in relation to its radius than a spherical patterned emmision.

If the radiometric outputs are the same, the radiometric emmision pointed in only 1 direction should keep greater intensity at a greater distance from the point source compared to a radiometric emmission emitting in all directions or a spherical pattern. One will disperse photons at a quicker rate with respect to distance (or its radius length) from the point source than the other.

EDIT:
I could be wrong I'll have to look

Groan....

ChiefRunningPhist said:

Its not that the ISL isn't observed, it's just that it's mis-interpreted. Same in the case of a laser. The ISL still holds true but the multiplying coefficient is different. Ill have to go back and review but the reason I'm saying that LED doesn't follow the most commonly modeled ISL is due to it being based on a spherical point source emmision with intensity diminishing on the surface of the sphere at a rate in relation to the inverse square of its radius length, whereas an LED emits in a cone shape and diminishes intensity at the surface of the cone at a different rate in relation to its radius than a spherical patterned emmision.

If the radiometric outputs are the same, the radiometric emmision pointed in only 1 direction should keep greater intensity at a greater distance from the point source compared to a radiometric emmission emitting in all directions or a spherical pattern. One will disperse photons at a quicker rate with respect to distance (or its radius length) from the point source than the other.

EDIT:
I could be wrong I'll have to look

Click to expand...

You seem to get that it still applies, but may have variables which impact the exact percentage of loss. I've encountered others that swear up and down that it doesn't apply at all to LEDs. From my research, it doesn't seem to be so much about the spherical vs conical emission, and more about the size of the emission point. Since the ISL describes a point source, which a single LED is pretty close to, so the law would apply almost perfectly to a single LED. But once you stack them together into a fixture and it increases the size of the "point source", it definitely changes the dynamics of the "multiplier" like you said.

I think that's basically why the Fluence style bar lights hold their intensity so well. They essentially increase the size of the emission source at which point the ISL just has to get looked at slightly different even though the principle still applies.

lol, no Luminus, WTH.

Thundercat said:

You seem to get that it still applies, but may have variables which impact the exact percentage of loss. I've encountered others that swear up and down that it doesn't apply at all to LEDs. From my research, it doesn't seem to be so much about the spherical vs conical emission, and more about the size of the emission point. Since the ISL describes a point source, which a single LED is pretty close to, so the law would apply almost perfectly to a single LED. But once you stack them together into a fixture and it increases the size of the "point source", it definitely changes the dynamics of the "multiplier" like you said.

I think that's basically why the Fluence style bar lights hold their intensity so well. They essentially increase the size of the emission source at which point the ISL just has to get looked at slightly different even though the principle still applies.

Click to expand...

Ya that could be, it's definitely peaked my interest, I looked at it again and this is kinda where I'm at..

If I had a tub of 100 rubber ducks and then a tub of 10 bars of soap, the rubber ducks would be in proportion to the bars of soap at 10 to 1, or the proportion of ducks would be 10× the amount of bars of soap. The inverse proption of ducks to soap would be 1/10. I could change the numbers of ducks to soap and realize different proportions, subsequently I could realize different inverse proportions too. Proportions, whether they are inverse or not, can be anything.

ISL just states that...

The intensity of an emmision is inversely proportional to the distance squared. - It doesn't give an exact inverse proportion, that's where the shape of the emmision comes into play.

A spheres outer surface area will increase faster than the outer curved surface area of a cone as the distance from the origin increases. Due to this, a spherical emission will have a greater intensity drop with respect to distance compared to a conical emmision of the same power despite both being inversely proportional to the distance squared, they just have different inverse proportions. Just like the tubs of ducks and soap, some emmision shapes have proportions of outer surface area much less than others despite still satisfying being inversely proportional to the square of the distance.

A laser changes its total surface area of emmision very little so the change in P/A with respect to distance from the origin is pretty small. A fire place emits in all directions and so the change in P/A with respect to distance from origin is much greater than that of a laser. Both examples diminish their intensity at some inverse proportion to the distance squared, but the inverse proportions are different.

That's my understanding atm but wish I felt more confident, I'm supposed to know this lol but it's been awhile.

Here's the link to the site I reviewed the most...
https://www.quora.com/Is-the-light-from-lasers-reduced-by-the-inverse-square-law-as-distance-grows-similar-to-other-light-sources

Its called inverse square "law" and that means nothing can change it.
For multiple 120° LED's you have at 1st to calculated the peak intensity at 0° and then the intensity at every 1°. With this data you can calculate multiple diodes incl. overlapping aso by creating an algorhythm.
We have discussed it back and forth around 2 years ago with a member called nofuckstogive (or so) and he has created an algorhythm to calculated ISL loss for multiple LED strips in tent or open space. Pretty smart guy but he is banned since then because he was unfortunately a dump arsehole because of too much alc., lol!

This was actually a calculator tool one can apply different canopy intensities to not just a picture. (See upper left corner)


He has created and it shows the more distance you use the more power you need to get 500μMol/s at canopy level. But it also shows the deeper penetration you get using more light from higher distance.
He has calculated all this using his algorhythm and he also had an own website but I've not stored any links. Maybe when you find the thread where we have dicussed about the ISL and how it applies with multiple diodes inside a tent the links are still there? But I don't know in which thread it was but it was not his own thread as far as I remember.

What you need are some IES files and a copy of DIALux - ten you can create as many PAR map simulations as you like.

Soon, physical PAR mapping will be dead.

Randomblame said:

Its called inverse square "law" and that means nothing can change it.
For multiple 120° LED's you have at 1st to calculated the peak intensity at 0° and then the intensity at every 1°. With this data you can calculate multiple diodes incl. overlapping aso by creating an algorhythm.
We have discussed it back and forth around 2 years ago with a member called nofuckstogive (or so) and he has created an algorhythm to calculated ISL loss for multiple LED strips in tent or open space. Pretty smart guy but he is banned since then because he was unfortunately a dump arsehole because of too much alc., lol!

This was actually a calculator tool one can apply different canopy intensities to not just a picture. (See upper left corner)
View attachment 4349119

He has created and it shows the more distance you use the more power you need to get 500μMol/s at canopy level. But it also shows the deeper penetration you get using more light from higher distance.
He has calculated all this using his algorhythm and he also had an own website but I've not stored any links. Maybe when you find the thread where we have dicussed about the ISL and how it applies with multiple diodes inside a tent the links are still there? But I don't know in which thread it was but it was not his own thread as far as I remember.

Click to expand...

Good info. Ill check the calculator out.

ISL is just describing the rate at which the outer surface area increases with respect to distance. Here's some SS's if you want claification from someone that is far more knowledgeable than me.

at the end of the day, you dont need 1000 PAR to create great buds,